DESCRIPTION (applicant's abstract): The relationship between neuropeptide expression and behavior is a rapidly expanding area of research within behavioral neuroendocrinology. Arginine vasopressin is involved in a number of social behaviors, such as social recognition, communicative behaviors, aggression, parental care and affiliation. The distribution of vasopressin receptors in the brain varies greatly among species with different social behaviors. There is a compelling need for a specific technique which will allow researchers to experimentally examine this receptor-behavior relationship. Voles provide an excellent model for the relationship between vasopressin receptor distribution and social behavior. For example, the highly social, monogamous prairie voles and the less social, promiscuous montane vole differ both in receptor distribution and the expression of behaviors regulated by vasopressin (pair-bonding, inter-male aggression, and paternal care). This proposal is designed to develop a technique by which one can experimentally manipulate vasopressin receptor expression in adult animals in a tissue-specific manner and investigate the behavioral consequences. We will develop two adeno-associated virus vectors containing the vasopressin receptor gene. Gene expression in one vector will be driven by the native vasopressin receptor promoter and in the other by a neuron- specific promoter. These vectors will be used to deliver the vasopressin receptor gene directly into the adult brain, via i.c.v. and site specific injections, and expression will be assessed using receptor binding assays. The regional specificity and temporal aspects of expression will be examined. To determine whether manipulating vasopressin receptor expression will affect behavior, animals will be subjected to a series of behavioral tests. At the conclusion of this project we will have a solid understanding of the degree to which this technology will provide a powerful new tool for neuroendocrine studies of the relationship of receptor expression and behavior. The vectors created here should be useful in other species for the study of aggression. territorial behavior and social memory.